Abigail "Abby" Williams, 13, and Liberty "Libby" German, 14, were found dead off a rural hiking trail near Delphi, Indiana, on Feb. 14, 2017.
More than two years later, authorities have yet to catch their murderer.
A timeline below shows how the case has unfolded so far.
Feb. 13, 2017
On the afternoon of Feb. 13, 2017, a family member drops off Abby and Libby at a trail near the scenic Monon High Bridge, an abandoned railroad bridge over Deer Creek in Carroll County, Indiana. While walking on the trail, Libby posts a photo to Snapchat showing Abby crossing the bridge.
Hours later, the girls failed to meet a relative, as planned, and were reported missing. A huge search gets underway but is called off when it gets too dark.
In a news release, Carroll County Sheriff Tobe Leazenby say there is no reason to suspect foul play or to believe the girls are in immediate danger.
Feb. 14, 2017
The search continues for the girls, and around noon, teams find two bodies about a half-mile away from the bridge.
Although authorities share the information with the media, they do not reveal the identity of the bodies.
Feb. 15, 2017
Autopsies are conducted on the bodies. That afternoon, Indiana State Police and the Carroll County Sheriff’s Department hold a news conference and confirm the bodies do belong to Liberty and Abigail. They say the girls were murdered.
“There is somebody out there who did this crime, and we’re going to find them,” says Indiana State Police Sgt. Kim Riley.
"We’re going to get to the bottom of this,” Leazenby says, “and do everything we can to use our resources."
Indiana State Police also release a photo of a man reportedly seen on the trail around the time the girls disappeared. The image shows a white male with his hands in his pockets while walking. He is wearing jeans, a navy blue jacket and a hat.
Police do not call the man a suspect but say they would like to talk with him.
Feb. 20, 2017
Police say they are searching for the man seen in the photo and encourage members of the public to call in with tips.
Feb. 22, 2017
At a news conference, police reveal Libby recorded video and audio of the suspect on her cell phone. The recording, which is released to the pubic, appears to capture a man's voice saying, "Down the hill."
"Somebody knows this voice," one Delphi citizen tells Inside Edition. "Somebody has to know who this guy is. We are begging you, begging you to come forward. We need to find out who has done this to our girls."
The release of the audio triggered more than a thousand tips. Citizen sleuths, including Nancy Grace, offered their theories about the killer.
"We hear that muffled: 'down the hill, down the hill' — Why was it muffled?" Grace tells ABC News. "Because I think she put it in her pocket. Now they are only releasing a portion of it, why? It could be an attack on the girls. It could even be their murders that they are not releasing to spare the families. But there's more proof on that video!"
Authorities also announce a $41,000 reward for information leading to an arrest.
March 1, 2017
The reward has now reached $200,000.
Abby Williams' grandparents leave an emotional note at police headquarters to expresses their gratitude for those investigating the case.
"We pray for your protection, and we are forever grateful for your service," the couple, Diane and Eric, write in the note.
March 9, 2017
Mike Patty, Libby's grandfather, speaks out for the first time at a news conference at the Carroll County Courthouse.
"This horrible crime has torn a hole in our families that will never heal," he says. "It’s the small things that seem to hurt the most. It's just natural to holler for them come to dinner; or in the mornings to get up and get ready for school, then expect them to come through the door after school; the silence when we don’t hear their voice."
He continues, "I don’t know exactly what happened out there that day, but I imagine there was probably an opportunity for one or both to separate and try to make a break different ways. But those girls loved each other. They were good friends. Neither one of them left each other's side."
He also thanked the community for its support.
"I can tell you that it's not easy, and a lot of people are putting a lot of work into this," he says. "We're hoping that the tip's there, and we're going to find it."
Authorities reveal the reward has jumped to $224,000 and police have received more than 11,000 tips, Fox 59 reported.
March 17, 2017
Indiana State Police, the FBI and Carroll County sheriff's deputies serve a search warrant at the home of Ron Logan, who owns the 30-acre property where Abby and Libby were found.
After their bodies were found, Inside Edition speaks to him about the discovery on his property.
“That was like being hit with a bolt of lightning. On my property! You just can't put words to it,” he said. "It was something I couldn't get my emotions around. You can't believe that something this terrible in this community happened here on my property, in my back yard."
He says he was buying tropical fish at the time of the murders.
Logan is later sentenced to two years for operating a vehicle after being a habitual traffic offender. He is accused of driving to the county dump on the day the girls vanished.
He is not facing any charges in connection with their disappearances or murders.
May 7, 2017
A group of local residents organize a community outing to the trail that the girls hiked the day they were killed. Dozens of people walked the Monon High Bridge trail together.
"The reality is that evil happened here, and so we want to reclaim this ground," Rev. Todd Ladd, pastor of Delphi United Methodist Church, says.
Days later, the community also hosts Abby & Libby Celebration of Life at Delphi Community High School to raise money for a softball complex planned in their memory.
July 17, 2017
Indiana State Police release a sketch of the murder suspect. The person depicted in the composite sketch is described as a white male between 5’6” to 5’10”, weighing 180 to 220 pounds, with reddish brown hair and eye color unknown.
July 18, 2017
The girls' families and friends gather to speak with Inside Edition.
“It’s like I had open-heart surgery, but they never used any anesthetic and they say, 'I’m sorry, you're just gonna have to live this way, with part of your heart missing the rest of your life,'" says Diane Erskin, Abigail’s grandmother.
They say they know the man responsible will be caught and brought to justice.
“We’re gonna get him,” one relative says. “We’re willing to wait. ... We’re willing to wait as long as it takes.”
Sept. 17, 2017
Authorities in Colorado arrest a man named Daniel Nations for having expired Indiana license plates. Police say he could be linked to the murders and call him a person of interest. It emerges he was homeless at the time of the murders.
Oct. 21, 2017
Nations' wife says he resembles the police sketch of the suspect but did not own the clothing seen in the photo.
"I can't tell if that is him or not," Katelyn tells The Gazette about the photo. "But the one thing I'm not going to buckle on, he did not have that jacket."
Dec. 14, 2017
The girls' families appear on the “Dr. Phil Show” to tell their story.
“My fear is that we could be here 10 years from now, and we won’t know what happened or why,” Abigail’s mother, Anna Williams, says on the show.
Liberty’s grandfather, Mike Patty, adds, "Somebody knows something. Nobody lives in total isolation in today’s world, and I’m asking that person, please help us out."
After the families' appearances on the show, police receive another 140 tips in the following days.
Feb. 14, 2018
Ahead of the first anniversary of the girls' deaths, authorities say Daniel Nations is not a suspect, KRDO reported.
"As you all know, we went out to Colorado and we spent a little bit of time with [Daniel Nations], and he's not a person we care a whole lot about at this time," Superintendent Douglas Carter with the Indiana State Police says at the news conference, KKTV reports. "Until somebody is arrested, we’re interested in almost everybody."
July 19, 2018
Speculation swirls that a man arrested in connection with a 30-year cold case could also be linked to the Delphi murders.
John Miller, 59, of Fort Wayne, Indiana, was arrested in the 1988 strangulation of 8-year-old April Tinsley. April’s body was discovered by a jogger three days after her disappearance in a water-filled ditch in a rural field.
Miller, who was arrested after DNA found on April was sent for testing, lived just two hours from Delphi. Miller was later convicted of the murder of Tinsley and sentenced to 80 years in prison.
When asked if Miller was a possible suspect, Indiana State Police Sgt. Kim Riley would not comment.
"We have 1,000 names out there, and we're still looking at all of them," Riley told the Journal & Courier, and said he was being intentionally vague.
Aug. 20, 2018
In an interview with The Gazette, Daniel Nations denies any involvement in the killings. He says he gave DNA samples to Indiana authorities.
"I feel like a victim in this situation," he says. "I just want people to know the truth, that I am not a monster."
Jan. 8, 2019
Charles Andrew Eldridge, 46, is taken into custody after allegedly arranging a meeting for sex with a police officer posing as a teen girl. He faces multiple charges, including two counts of child molestation, and is currently being held without bond. He has not yet entered a plea.
During the course of news coverage of his arrest, local Indiana residents notice his mugshot resembles the sketch of Abby and Libby's alleged killer and begin calling the police tip line.
After receiving multiple calls, Capt. Dave Bursten of the Indiana State Police assures the public the task force dedicated to finding the teens' case investigates every tip.
“I can promise you this: When an arrest is made of a suspect identified ... as the alleged perpetrator of the Delphi Murders, rest assured, we will let everyone know," Bursten said in a statement.
State police's statement added, "It is important for the public and media to know that many similar tips and arrests of other persons alleged to be connected to the Delphi murders occur with some frequency in and outside of Indiana. Each tip - whether it receives media attention or not - is investigated for any connection to the Delphi case.”
Jan. 10, 2019
Indiana police say there is no evidence thus far to suggest Eldridge has any connection to the case.
In a news release, Randolph County police said "outside of the person resembling the sketch, there is currently zero evidence that ties him to this case and he is not a suspect in the case."
"Although we understand that people are trying to help the investigation, by doing this with zero evidence other than a mere appearance, it can also hurt or hinder an investigation," the department said.
Jan. 21, 2019
Capt. Dave Bursten says there is no evidence suggesting or disproving whether Eldridge is connected to the case, according to a report.
Speaking to Inside Edition, Libby's grandparents say they will wait for information from authorities before getting too hopeful.
"We've been down this path a few times on a few other tips similar to this," Libby's grandfather, Mike Patty, said. "We're really going to wait until we get something from law enforcement."
Inside Edition's Steven Fabian asked, "If this does pan out, what would that mean to you and your family?"
"There'll never be closure," Patty said. "We've lost our girls. They're not coming back. But at least it would allow us to move on from this chapter to the next so we could all start to heal because right now, it's just kind of an open wound."
Feb. 13, 2019
On the two-year anniversary of the girls' disappearance, authorities vowed they would bring the person responsible to justice.
“This is not a cold case,” Carroll County Prosecutor Nicholas McLeland told reporters. “This case is not closed. We are not done with this investigation — there are countless people working on this every day.
“This case has affected the community in so many ways,” McLeland continued. “The people behind the scenes will not rest until we get this case solved. Abby and Libby deserve that kind of dedication, not only from me but from everybody involved.”
Anyone who comes forward with the information is asked to include, if possible, a suspect’s name, date of birth or approximate age, physical description, their address, vehicle information, a specific reason why they believe this person should be considered a suspect, a possible motive and any connection that person may have to Delphi.
“We want to encourage people to continue to call in with any information that they may have,” McLeland said. “I always use the adage of, ‘If you see something, say something.’ Nothing is going to be considered a ‘dumb tip’ or a tip that we don’t want. Information is our main weapon here.”
Feb. 14, 2019
Loved ones and community members gathered to remember the girls two years after their bodies were found. It’s their hope that the second anniversary of their death is the last they mark without having answers.
“We’ve been saying it all along: Someone knows something,” Mike Patty, Libby’s grandfather, told the Lafayette Journal & Courier. “Someone’s going to talk. Someone’s going to think, ‘Maybe this one thing I saw might mean something.’ And maybe that’s the one thing that gets this guy.”
April 22, 2019
The Indiana State Police release new audio, new video and a new sketch of the suspect as they announce a "new direction" at a press conference.
Never-before-released video taken from Libby's cellphone shows a man walking toward the two girls. (A still image from the video had previously been shared.) Authorities also release more phone audio in which a man apparently orders them "down the hill."
They also share a new, younger-looking sketch of the suspect, who they believe lives or has lived in Delphi. They believe he still visits the area. Authorities say he is between 18 and 40, but said he may appear older than he is.
A reward for information leading to an arrest now stands at $225,000.
May 13, 2019
State police said that in the wake of the new evidence released in April, more than 3,000 new tips have come in, including thousands of emails, more than 500 calls to the tip line and nearly 150 calls and/or walk-ins to local police departments.
Police reiterated that it's important to be as specific as possible.
"Please remember that we are looking for information that could lead to the arrest and conviction of the person or persons who committed this crime," Indiana State Police said in a statement.
Got a tip? Email Abbyandlibbytip@cacoshrf.com or call the tip line at 844-459-5786.